#include<iostream>
using namespace std;
int main()
{

   int p,d,m,s,ns,count=1;
   
   cin>>p>>d>>m>>s;
   ns=s;
   s-=p;
   while(p>m)
   {
      s-=d;
      p-=d;
      count++;
   }
   if(s>m&&d<m)
   {
      while(s>m)
      {
         s-=d;
         count++;
         break;
      }
   }

   cout<<count;
}